Furnace for burning solid fuel.



A. VINCENT & 0'. MUIR. FURNACE FOR BURNING SOLID FUEL.

APPLICATION FILED JUNE 7 1911.

Patented Nov. 19, 1912.

8 SHBETSSHEET l.

45 m MM) lnvanfors W4 67 Afforney WIT/1 cssas A. VINGENT & O. MUIR.

FURNACE FOR BURNING SOLID FUEL. APPLICATION FILED JUNE 7, 1911.

1 344,71 1 Patented Nov. 19, 1912.

3 SHEETS-SHEET 2.

WT Invenfors I misses M W AfT OVVICJ/ COLUMBIA PLANOGRAFH Cm, WASHINGTON. D. c.-

A. VINCENT & G. MUIR.

FURNACE FOR BURNING SOLID FUEL.

APPLICATION FILED JUNE 7, 1911.

Patented Nov. 19, 1912.

3 SHEETS-SHEET 3.

M /37 A orney FIG. 9

Wifncssas $W COLUMBIA PLANOGRAPH C0. WASHINGTON. D, C.

UNITED erm ne BATENT onFio ALFRED VINCENT, OF REDFERN, AND CHARLES IVIUIR, OF ST. PETERS, SYDNEY, NEW SOUTH WALES, AUSTRALIA, ASSIGNORS TC MUIR-VINCENT SMOKE CONSUMERS LIMITED, OF SYDNEY, AUSTRALIA.

FURNACE FOR BURNING SOLID FUEL.

To all whom it may concern Be it known that we, ALFRED VINCENT and CHARLES Mum, subjects of the King of Great Britain and Ireland, and residents, respectively, of 8 Golden Grove street, Redfern, Sydney, New South Wales, Australia, and of 88 Sutherland street, St. Peters aforesaid, have invented new and useful Improvements in Furnaces for Burning Solid Fuel, of which the following is a specification,

Our invention relates to furnaces for boilers and other apparatus, in which solid fuel is burned under natural draft or artificial draft.

It consists in certain improvements in the type of furnace in which the furnace door is formed as an air preheating chamber and air draft distributing device, and in which the furnace bridge is split or perforated or mouthed for the purpose of introducing a supplementary preheated draft of air at the rear of the fire.

It is well known that advantageous results are obtained by preheating the air draft to a furnace and dispersing and evenly distributing air over the fire, and it is also well known that the preheating of supplementary air introduced at or about the furnace bridge is desirable in order to complete the combustion of partially burned gases under conditions which inhibit cooling down of the products of combustion before the same pass to the heating surfaces beyond the furnace bridge. Many forms of apparatus for these purposes are known, in which the air is preheated in passing through a chamber formed on the back of the furnace door I and is dispersed and distributed over the fire through vents in said chamber, and in which supplementary air is drawn from the ashpit through a chambered bridge and emitted into the furnace through vents in the front, rear, or top of said bridge.

Our invention consists in an improved preheating device for furnace doors and bridges, which device is constituted of a grating or screen composed of two sets of T-bars arranged in alternated order so as to leave zig-zag passages between them, through which passages the infiowing air is caused to pass. in thin streams and is heated by contact with the T-bars, which are exposed to the heat of the fire. The heat- Speeification of Letters Patent.

Application filed June 7, 1911.

Patented Nov. 1 9, 1912.

Serial No. 631,856.

ing chamber on the door which carries the T-bar screen is fitted with dampers on the front plate to regulate the air intake, and with a back plate which is perforated to admit preheated air over the fire in a large number of fine jets. As applied to the bridge, the grating of T bars is made to form the forward side of a chamber the back of which is the usual bridge wall, said chamber being covered with a flat plate of metal, and being left open to the ashpit on its bottom side. The T-bar grating subdivides and distributes the inflowing stream of air more or less equably across the whole width of the bridge, and raises its temperature, for which purposes it has a high efficiency. Being located in the hottest region of the furnace, its temperature is high, and as the exposed surface is large (proportionately to the area of the grating) and the direction of the incoming air is twice altered as it passes'between the bars, said air becomes heated rapidly and practically uniformly. The construction is such that fouling by ash does not occur, as the bars act after the manner of ordinary grate bars and allow ashes to pass between them into the ashpit. Their heavy section militates against risk of accidental breakage in cleaning fires, and as they are separately replaceable, the cost and delay common to repair or renewal of air feed bridges of most other forms are avoided. An air preheating device similarly constructed may be applied also at the rear end of a locomotive grate below the usual firebrick battle, with an open rear space above the ashpit.

In the accompanying drawings :-Figure l is a. perspective vertical sectional elevation illustrating the application of our invention to a bridge of'a boiler furnace of a common type; Fig. 2 is a corresponding horizontal section taken at the level of the horizontal arrows in'Fig. 1; Fig. 3 is a vertical perspective sectional elevation through a locomotive furnace to which a similar bridge is applied; Fig. 4 shows in perspective two of the T-bars which are used to form the preheating grating; Fig. 5 is a perspective view nal structure of the preheating chamber in the door shown in Fig. 5; Fig. 7 is a horizontal section through the door and preheating chamber; Fig. 8 is a vertical section through the same; and Fig. 9 is a longitudinal section through a boiler furnace of usual type having fitted to it a preheating door and an additional air preheater in the bridge according to our present invention.

Referring to Figs. 1, 2, and 4, A is a transverse bearer which supports the rear ends of the firebars B. It is located a little forward of the bridge wall C and serves to carry the grated structure E formed of T- bars (see Fig. 1') through which additional air is admitted to the rear of the furnace. D is the space rearward of the grating of T-bars E, and F is the ashpit. A. brick sill G is set on the bearer A, and is covered with a ribbed or grooved foot plate H into which the lower ends of the T-bars E are set. The cover plate J is ribbed on the underside as shown at Z to set over the heads of the T- bars E, and to anchor them back to the bridge wall C. The front end of the cover plate J forms a hood K which overhangs the inner face of the grating bars. The ribbed or grooved form of foot plate and cover plate illustrated makes an effective frame for the ends of the T-bars, but is not otherwise necessary; this particular detail may therefore be varied in any'manner de sired so long as a satisfactory support or frame for the T-bars is provided. It is very desirable that the cover plate J should be made with a forwardly extended hood K as illustrated. The T-bar grating is not required to extend the full width of the furnace. In practice it is found quite satisfactory if it extend for about three-fourths of the furnace width.

Referring to Fig. 3, P are the firebars, Q shaking bars for clearing ashes, and R a brick baffic perforated with a large number of conical holes S. T and U are foot and head frames carrying the louver of T-bars E, and W is a brick sill under the foot frame T. The heads of the T-bars may be built into the battle R and the head frame U dispensed with, but we prefer the construction shown. Y is a clear space rearward of the louver E; its lower side is open to the ashpit.

Referring to Figs. 5 to 9, a is the front plate of the furnace door, I) the sides of the air preheating chamber 0, and (Z the back plate of the chamber 0. Small holes 6 are provided in the plate cl forming passages for air from the preheating chamber to the space above the fire in the furnace, and verticalslots are provided through the door front plate a. g is a slotted register plate the slots in which register with the slots f. This plate 9 isslidablej across the; rear face of the plate (1* means of a hand knob 5 'ing.

which projects through a clearance gap 1' in one of the bars of the front plate a. is are independent slide plates slidable through rabbet fillets Z pinned to the plate a, and m are strips secured to the top and bottom sides of the preheating box to form guideways for the slot-ted slide plate 9. E are the T-bars which are made of cast iron and arranged as a vertical grating in the preheating box. The bars E are held between the integral flanges m and the separately secured flanges a.

The T-bars which constitute the preheating grating in the door and at the back of the furnace are clearly illustrated in Fig. 4, L being the flanges or faces, and M the web. The spacing paps or bosses N as shown do not extend the full width of the flange, but they may be made flush with the flanges.

In operation, air passes through the slots f in the door plate a under natural draft or forced draft, and in such volume as is permitted by the open area of said slots, which area is controlled by the setting of the register plate and the slide plates 70. The preheating chamber 0 and the T-bar E grating within it and the perforated back plate (Z are heated by radiation from the fire. In passing from the front to the back of the preheating chamber 0 the temperature of the inflowing air is raised by contact with the grating of zig-zagged T-bars E. In passing through the zig-zag passages be tween the T-bars E the course of the air altered and it is thoroughly intermixed, whereby a uniform temperature is assured. The uniformly heated air finds exit through the perforations 6 into the space above the fire and supplies to the fire the necessary volume of oxygen in a preheated condition for promoting satisfactory combustion. The construction of door front plate a with register slide damper plate slotted precisely as shown is not essential. It will sufiice if the front plate a be fitted with any other form of register or damper by which volume of air flow may be readily controlled and air admitted in dispersed streams or currents to the chamber 0 in front of the T-bar grating E. Additional air passes from the ashpit up into the free space D, thence takes a Zigzag course between the T-bars E, becoming heated by contact with them, and finally passes forward in distributed streams into the furnace and mixes with the gaseous products of combustion which are passing toward and over the top of the bridge. The quantity of air so admitted is controlled by working the fire toward or away from the grating of T-bars E. The draft can be di- 'mi'nishe'd to any desired extent by working fuel and ashes back against the T-bar grat- When. the fire israked forward maxibridge draft is admitted.

' Tue opera-tics of the piers-area as shown in Fig. 8 is as follows :As in the case of the ordinary bridge type of furnace, the open area of the T bar grating E for air ad mission is controlled by worklng the fire toward or away from the grating. Air passes from the ashpit up through the space Y and thence through the zigzag passages between the T-bars E forming the grating, becoming heated by contact with the bars and passing into the furnace in subdivided streams. The holes S allow gases to pass through the brick baffle It and serve to promote intermixture of the air and gases be fore same pass to the tube plate.

lVe do not herein claim specifically the combination of our improved preheating grate with the furnace door features as shown in Figs. 5 to 9, this construction being shown and claimed in our co-pending application for improvements in boiler furnace doors, Serial No. 669,410, filed January 4, 1912, as a division of this application. In the present application we present claims to the improved grating broadly considered, and also more specific claims relating to the combination of the grating with the part-s at the back of a furnace as shown in Figs. 1 to 3 and f).

VVhatwe claim as our invention and de sire to secure by Letters Patent is z- 1. The combination with walls forming an air preheating passageway for fuel burning furnaces, of an air heating and dispersing grating through which the incoming air passes, the grating being composed of spaced bars T-shaped in cross section and arranged in two series, the bars of one series alternating with the bars of the other, the flanges of the bars of one series being at one side and the flanges of the bars of the other series being at the other side, whereby zigzag passages are formed between the bars.

2.. A draft preheating and dispersing grating for furnaces, composed of bars T- shaped in cross section and arranged with the flange of each bar positioned on the opposite side from the flange or flanges of the neXt adjacent bar or bars, and bosses on the bars for spacing them apart to leave zigzag apertures between them.

3. In a furnace, the combination with a fire grate, an ash pit and an open bottomed chamber at the rear end of the fire grate and above the ash pit, of a grating between the said chamber and the combustion space above the fire grate consisting of spaced bars T-shaped in cross section and arranged with the flange of each bar on the opposite side from the flange or flanges of the next adjacent bar or bars whereby zigzag passageways from the chambento the combustion space are formed between the bars.

4. In a furnace, the combination with a fire grate, an ash pit and an air feed chamber at the rear end of the fire grate and communicating with the ash pit, of a metal plate forming the top of the air feed chamber, and a series of spaced bars T-shaped in cross section and engaging at their upper ends with the plate and arranged with the flange of each bar on the opposite side from the flange or flanges of the adjacent bar or bars, whereby zigzag passageways from the air feed chamber to the combustion space of the furnace are formed between the bars.

5. The combination with a hollow bridge for a furnace, of a vertical grating constructed of spaced bars T-shaped in cross section and arranged with the flange of each bar disposed on the opposite side from the flange or flanges of the adjacent bar or bars, the said bars forming the front of said hollow bridge, and operating to preheat in flowing air and deliver the same in dis persed heated streams into the flow of furnace gases passing toward said bridge.

6. In a locomotive boiler furnace, the combination with an ash pit. a tire grate, and an arch above the grate, of an air duct at the rear end of the fire grate open to the ash pit, and a vertical grating located underneath the arch between the end of the fire grate and the air duct and comprising spaced bars T-shaped in cross section and arranged in two series, the bars of one series alternating with those of the other, and the flanges of the bars of one series lying at one side and the flanges of the bars of the other series lying at the other side.

7. In a locomotive boiler furnace, the combination with an ash pit, a fire grate, and an arch above the grate, of a device for in troducing additional air in dispersed streams and in a heated condition at the rear end of the grate, consisting of a vertical grating composed of spaced bars T- shaped in cross section and arranged with the flange of each bar on the side opposite to the flange or flanges of the next adjacent bar or bars, the said grating forming the front side of a chamber below the arch, the bottom of which chamber is open to the ash pit.

In witness whereof we have hereunto signed our names this 27th day of April 1911,'in the presence of two subscribing witnesses.

ALFRED VINCENT. CHAR-LES IWUIR. Witnesses M. J. GANDRIGK, W. J. DAVIS.

Copies of this patent may be obtained for five cents each. by addressing the Commissioner of Patents,

Washington, D. G. M 

